The present invention relates to a multi-piece circuit board constituted so that a plurality of piece section are included in one board. More specifically, the present invention relates to a multi-piece circuit board (so-called jigsaw board) constituted so that only good piece sections are included in one board and to a manufacturing method therefor.
There is known, as a circuit board, a multi-piece circuit board constituted so that a plurality of piece sections are included in one board. As for multi-piece circuit boards, it is sometimes required, for example, that all piece sections are good pieces to meet the demand of later steps. In actual process, however, it is difficult to completely prevent a multi-piece circuit board including defective piece sections. Nevertheless, it is disadvantageous in terms of the effective use of resources to scrap other good piece sections in a multi-piece circuit board because at least one failure piece section is included in the board.
Considering this, if there is a board which includes both defective piece sections and good piece sections (to be referred to as xe2x80x9cmixed boardxe2x80x9d hereinafter), the defective piece sections are removed from the circuit board, good piece sections which are detached from another mixed board are attached to a resultant vacant location and a so-called jigsaw board is thereby provided. By doing so, it is possible to provide a multi-piece circuit board constituted so that all piece sections are good piece sections to later steps while making effective use of resources.
However, according to the conventional jigsaw board, the attachment and detachment of a piece section is conducted by cutting off and joining bridges which couple piece sections to a frame section after forming an outermost layer. This causes the following disadvantages. Namely, a difference in height may possibly occur among the frame section, piece sections which are originally loaded to the frame section and the piece sections attached later to the frame section by cut-off and bonding. Due to this, in the later step of printing solder paste to, for example, mount electronic components, good printing cannot be performed because of the difference in height on the surface of the circuit board. In this case, because of insufficient soldering, there is high probability of occurrence of defects. In addition, since the strength of a bridge (joint section) is lowered by cut-off and bonding, there is a probability that attached pieces unexpectedly come off in later steps.
Furthermore, since a conventional jigsaw board is a circuit board which is manufactured so that all the sections including the frame section are integrally manufactured except for the piece sections attached in place of defective piece sections, all the sections are made of similar materials. This causes the following disadvantage. In the later step of handling the multi-piece circuit board, it is required that the frame section has a certain degree of strength for operation. On the other hand, the piece sections which form a part of a finished product recently tend to be made thinner to satisfy the demand of providing a compact product. As the piece sections are made thinner, the frame section becomes thinner, accordingly. Due to this, to make the piece sections thinner is a trade-off for the requirement of strength. To ensure required strength, the width of the frame section may be increased. If so, however, number of piece sections per board cannot be increased.
Moreover, the frame section becomes unnecessary after the piece sections are employed. However, since the frame section is basically made of the same material as that of the piece sections, it is not always easy to dispose of or recycle the frame section.
The present invention has been, therefore, achieved to solve the above-stated disadvantages. Specifically, the object of the present invention is to provide a multi-piece circuit board and a manufacturing method therefor capable of ensuring flatness between a piece section after cutoff and bonding and the other sections even if one piece section is cut off and another piece section is bonded, preventing the lowering of the strength of a joint section and determining the material of a frame section irrespectively of piece sections.
A multi-piece circuit board according to the present invention which has been achieved to solve the above-stated disadvantages is a multi-piece circuit board comprising: a frame section; and a plurality of piece sections connected to the frame section, characterized in that a joint is provided in an inner layer at a connection portion of said frame section and a piece section for at least one piece section, and the joint is covered with an upper layer. It is noted that xe2x80x9cthe upper layerxe2x80x9d includes all layers provided outside of the layer on which the joint is present. For example, if a solder resist layer has sufficient junction strength, the solder resist layer solely may compose the upper layer.
In this multi-piece circuit board, the joint between the piece sections cut off and bonded and the frame section is present in an inner layer in the connecting portion. Here, the joint may be present in the connecting portion itself (so-called bridge) or in the frame section or the piece section in the neighborhood of the connecting portion. If the joint is present on the piece side, however, the presence of the joint in the piece section causes a damage to the piece section which becomes a product and this is not, therefore, impractical. As can be seen, the attachment and detachment of the piece section are conducted by cutting off and coupling the connected portion in which the piece section is connected to the frame section. Due to this, there can be an aspect fearing of the lowering of the strength of the joint portion formed by cutoff and bonding. However, the joint is present in the inner layer in the connected portion and the joint is surely covered with the upper layer. In other words, the upper layer reinforces the strength of the joint section. As a result, the lowering of the strength of the joint section is prevented. It is, therefore, possible to give the same strength as the inherent strength of the circuit board to the joint section. It is thereby possible to prevent the piece section from unexpectedly coming off in later steps.
Further, the joint is covered with the upper layer. That is, after the frame section is coupled with the piece sections by the joint, the upper layer is further provided. In addition, since pressing is performed when forming the upper layer, it is possible to secure the flatness between the piece section cut off and bonded and the other sections. Besides, since the joint is covered with the upper layer, the joint is invisible from the outside and good appearance is obtained accordingly.
A method for manufacturing a multi-piece circuit board according to the present invention is a method for manufacturing a multi-piece circuit board comprising a frame section and a plurality of piece sections connected to the frame section, which method is characterized by, if a plurality of multi-piece sections each including a defective piece section and a good piece section in a state in which an outermost layer is not formed yet, making a cut line around the defective piece section on one of the multi-piece circuit boards, and removing the piece section; similarly getting out the good piece section of another multi-piece circuit board; inserting the good piece section gotten out of the other multi-piece circuit board into a vacant location from which the defective piece section is removed; and providing an upper layer to cover a joint in that state.
According to this manufacturing method, a defective piece section is gotten out of one mixed board on which an outermost layer pattern is not formed yet. A cut line at this time may come into a connecting portion or the neighborhood of the connecting portion or, to be specific, into a bridge which couples the piece section to the frame section or the frame section in the neighborhood of the root of the bridge. Likewise, a good piece section is gotten out of another mixed board on which an outermost layer pattern is not formed yet. The two cut lines are joined together. As a result, a joint is formed. In a state in which the joint is formed, an upper layer is further provided to cover the joint. Consequently, the multi-piece circuit board having a joint present in an inner layer in a connected portion is manufactured.
Further, in the method for manufacturing a multi-piece circuit board according to the present invention, it is preferable that after joining cut lines together by adhesive, the upper layer is provided. This is because the junction strength of the joint is secured by the adhesive. By fully covering the joint with the upper layer, the strength of the joint is reinforced. It is, therefore, possible to ensure preventing the lowering of the strength of the joint section formed by cutoff and bonding.
In the method for manufacturing a multi-piece circuit board according to the present invention, it is also preferable that a member containing an adhesive component is employed as the upper layer. This is because the adhesive component contained in the upper layer is effused into the joint when providing multiple layers to thereby bond the cut lines to each other. Further, the strength of the joint section is reinforced by the upper layer, whereby it is possible to ensure preventing the lowering of the strength of the joint section formed by cutoff and bonding.
Further, another multi-piece circuit board according to the present invention is a multi-piece circuit board comprising: a frame section; and a plurality of piece sections connected to the frame section by bridges, respectively, characterized in that the frame section is obtained by molding out of fluid matter, and the plurality of piece sections are manufactured before molding of the frame section.
Furthermore, according to a method for manufacturing a multi-piece circuit board according to the present invention, in the manufacturing of a multi-piece circuit board comprising a frame section and a plurality of piece sections connected to the frame sections by bridges, respectively, the respective piece sections manufactured in advance are arranged at positions at which the piece sections are to be present in the multi-piece circuit board; and a fluid matter is injected to surround the respective piece sections arranged to form the frame section using the fluid matter. The above-stated multi-piece circuit board is thus manufactured.
In the multi-piece circuit board, the fluid matter is formed into the frame section. It is, therefore, possible to select a fluid matter irrespectively of the material of the piece section. Accordingly, it suffices to select a material which can be easily disposed of or recycled after the piece section is removed in a later step.
It is preferable that this multi-piece circuit board further includes a protrusion at a position coming into the frame section, and that the protrusion is connected to the piece section by the bridge and manufactured together with the piece section. As a result, a larger junction area is secured between the piece section and the frame section. Consequently, it is possible to further ensure obtaining the junction strength between the piece section and the frame section.
To this end, in the manufacturing thereof, portions having protrusions connected by the bridges may be employed as the respective piece sections arranged, and by forming the frame section using the fluid matter, the protrusions may be turned into a state of coming into the frame section.
Further, it is preferable that when forming the frame section, the fluid matter is injected from a position outside of an edge of the frame section on the multi-piece circuit board when forming the frame section, and that a convex section at the injection position is broken off after forming the frame section. By doing so, it is possible to ensure the better flatness of the frame section. That is, a convex fin is inadvertently formed in the portion of the injection port. By breaking off the portion, no fin is provided on the resultant frame section.
Further, another multi-piece circuit board according to the present invention is a multi-piece circuit board comprising: a frame section; and a plurality of piece sections connected to the frame sections by bridges, respectively, characterized in that all of the plurality of piece sections are manufactured separately from the frame section, and coupled to the frame section. In addition, in a method for manufacturing the multi-piece circuit board according to the present invention, a frame section having a plurality of vacant locations for arranging a plurality of piece sections and the plurality of piece sections manufactured separately from the frame section are prepared, the piece sections in the vacant locations of the frame section are arranged, respectively, and that the piece sections are coupled to the frame section to thereby provide the multi-piece circuit board.
In this multi-piece circuit board, the frame section is manufactured separately from any one of the piece sections. In other words, this multi-piece circuit board is constituted by separately manufacturing the piece sections from the frame section and the piece sections are coupled to the frame section. It is, therefore, possible to easily make all the piece sections good piece sections and also possible to set the material of the frame section different from that of the piece section. Consequently, even if the piece sections are thin, it is possible to secure strength without increasing the width of the frame section.
It is more preferable that the multi-piece circuit board according to the present invention is constituted so that joints between the respective piece sections and the frame section are provided on the frame section to surround roots of the respective bridges. Further, it is preferable that in the method for manufacturing the multi-piece circuit board according to the present invention, members each having a functional portion which includes a wiring pattern and a protrusion which is provided around the functional portion are employed as the piece sections, respectively and that a member having a concave section which corresponds to the protrusion and which is provided at edges of each of the respective vacant locations is employed as the frame section.
By doing so, the area of each joint between each piece section and the frame section is set larger than that of the joint provided on the bridge. Due to this, the junction strength is high to thereby prevent the piece section from unexpectedly coming off in a later step.
Furthermore, another multi-piece circuit board according to the present invention comprises an adhesive sheet covering a joint between the frame section and each of the piece sections to spread over the frame section and the piece section. As the joint, there is a joint which couples the piece section having a protrusion to the frame section having a concave section corresponding to the protrusion of the piece section, or the like.
In this multi-piece circuit board, the junction strength between each piece section and the frame section is high. In addition, if the piece section includes a protrusion and this protrusion is applied as a protrusion fitted into the concave section of the frame section, then it is possible to obtain higher junction strength by covering the protrusion and the corresponding concave section with the adhesive sheet without bonding the sheet to the main body section of the piece section.
According to a method for manufacturing a multi-piece circuit board according to the present invention, in the method for manufacturing a multi-piece circuit board comprising a frame section and a plurality of piece sections connected to the frame section, the frame section and the piece sections are fitted into each other in advance and the joints are covered with an adhesive sheet later. As a result, the above-stated multi-piece circuit board is manufactured.
Furthermore, it is preferable that a metal foil is provided on a surface of the adhesive sheet between each piece section and the frame section. By doing so, it is possible to decrease the cracking of the multi-piece circuit board. It is also possible to decrease the flow of resin.
Moreover, if a member having a positioning target pattern is employed as the piece section, the positioning target pattern section is sometimes concealed by an adhesive sheet. It is, therefore, preferable to cut off the corresponding portion of the adhesive sheet in advance so as not to conceal the positioning target pattern. By doing so, it is possible to employ the positioning target pattern without being covered with the adhesive sheet.